Amplifying apparatus



M. C. A. LATOUR.

' AMPLIFYING APPARATUS.

APPLICATION FILED JUNE 8,1918.

Patented June 28, 1921.

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Attorney.

UNITED STATES .PIENT -ole-ace.

MARIUS C. A. LATOUR, OF PARIS, FRANCE.

mmrYine APPARATUS.

To all-whomz'tmay concern.

Be it known that I, MARIUS C. A. LATOUR, a citizen of the Republic ofFrance, residing at Paris, France, 10 Rue Auber, have invented certainnew and useful Improvements in Amplifying Apparatus, for which I havefiled applications in England September 12, 1917, Patent No. 129,659,and in France September 12, 1916, of which the following is aspecification.

This invention relates to an improvement in or modification of theamplifying devices described in the specification of m prior patentapplication No. 209,269 filed ecem ber 28,1917.

' It is well known that the use of thermionic amplifiers is impeded bysounds of whistling, grating, etc, which are sometimes heard and whichare very prejudicial to the normal Working of the apparatus; theseabnormal phenomena have been attributed to the setting up ofoscillations in the thermionic lamp facilitating the production ofvibration or auto-excitation, but their source is obscure and notentirely understood.

In the said prior specification a means of obviating these undesirablenoises in the amplifiers has been indicated consisting in defining thepotential of the casings, frames or cores of the transformers and of theprimary of the first transformer which supplies the current that is tobe amplified.

According to the present invention an improved elimination of theseobjectionable noises is obtained by defining also the potential of theframe or casing of the telephone headpiece and in some cases also thepotential of the operator. A still further improvement is sometimesobtained by defining also the potential of the earth with respect to thesystem. This is attained by connecting one pole of the main battery tothe earth.

The present invention is illustrated in the accompanying drawing by wayof example as applied to a two-stage amplifier.

' Figures 1, 2 and 3 illustrate three modifications in diagrammaticnianner. Similar references denote similar parts in all three figures.

In said drawing T T T represent the transformers, the cores of which aredenoted by M M and M respectively. The two thermionic valves 1 eachcomprlse a plate 2, a grid 3 and a filament 4, the latter supplied withcurrent from a battery 5. P is the Specification of Letters Patent.

Application filed June 8,

Patented J nne 28, 1 921.

1918.' Serial No. 239,019.

main battery one pole of which is earthed and Z the telephone headpiece.

In order to connect the mass of the telephone head piece Z to a point onthe battery all that is required is to connect one terminal of thetelephone circuit to the, said point on the cell and to connect thecorresponding terminal of; the telephone to the head piece. By doingthis the connection is made through one of the conductors of thetelephone cord itself.

The secondary winding of the transformer T the potentialof Which isdefined by connecting one of its terminals to the battery 1n order toavoid objectionable noises within the. thermionic valve, could, in fact,feed any external circuit.

Instead of connecting one terminal of the transformer T or T to thebattery as shown in Fig. 1 one might connect to the battery the centraloint of the corresponding transformer winding as shown in Fig. 2 or thecentral point of a resistance or impedance connected in parallel withthat Winding, as shown in Fig. 3.

The connections from the batterv to the different windings or masses toearth can beestablished through impedance capacities or resistances.

A-two-stage amplifier has been illustrated in the figure, but it goeswithout saying that the arrangement is suitable generally for anamplifier having any number of stages.

What I claim as new, and desire to secure by Letters Patent of theUnited States, is:

1. In an amplifying apparatus for wireless signals and the like, athermionic valve, a source of current in circuit therewith, a telephone,a transformer having a winding in circuit with said thermionic valve andsource of current and a winding in circuit a source of current incircuittherewith, a

telephone, a transformer having a winding 1n circuit with saidthermionic valve and source of current and a winding 1n clrcuit withsaid telephone, and a connection between the frame or casing of saidtelephone, the transformer winding in circuit with said telephone andone pole of saidsource of current, said connection being grounded.

4. In an amplifying apparatus for wireless signals and the like, athermionic valve, a source of current in circuit therewith, a telephone,a transformer having a winding in circuit with said thermionic valve andsource of current and a winding in circuit with said telephone, a metalcore for said transformer, and a connection between the frame or casingof said telephone, said metal core and one pole of said source ofcurrent, said connection being grounded.

5. In an amplifying apparatus for wireless signals and the like, athermionic valve comprising two electrodes and a grid, a source ofcurrent in circuit with said electrodes, a telephone, a transformerhaving a winding connected with said grid and one of said electrodes, asecond transformer having a winding in circuitwith said electrodes andsaid source of current and a winding in circuit with said" telephone,and a connection between the frame or casing of said telephone, awinding of each of said transformers, and a pole of said source ofcurrent.

6. In an amplifying apparatus for wireless signals and the like, athermionic valve comprising two electrodes and a grid, a

source of current in circuit with said elec" trodes, one pole of saidsource of current being grounded, a telephone, a transformer having awinding connected with said grid and one of said electrodes, a secondtransformer having a winding in. circuit with said electrodes and saidsource of current and a winding in circuit with saidtelephone, and aconnection between the frame or casthe grid and one electrode of one ofsaid valves, another of said transformers having a winding in circuitwith the electrodes of another of said valves and a winding in circuitwith said telephone, and a connection between the frame or casin of saidtelephone, the transformer windlng adapted to be connected to anexternal circuit, the transformer winding in circuit with saidtelephone, and one pole of said source of current.

8. In an amplifying apparatus for wireless signals and the like, asource of current, one pole of said source of current being grounded, atelephone, at thermionic valves connected in parallel with said sourceof current, each valve comprising two electrodes and a grid, n+1transformers connected with said valves, an iron core for each of saidtransformers, one of said transformers having a winding adapted to beconnected to an external circuit and a winding connected to the grid andone electrode of one of said valves, another of said transformers havinga winding in circuit with the electrodes of anotherof said'valves and awinding in circuit with said telephone, and a connection between theframe or casing of said telephone, said iron cores, the transformerwinding adapted to be connectone pole of said source of current.

In testimony whereof I aflix my signature in presence of two witnesses.

' MARIUS C. A. LATOUR. Witnesses:

EUGENE Jr'ln'ron, CHAS P. PRESSLY.

ved to an external circuit, the transformer winding in circuit with saidtelephone, and

